1. Field of the Invention
This invention generally relates to copying a magnetic record previously recorded on a magnetic master medium onto a blank magnetic copy medium, and is specifically directed to bulk duplication of magnetic records onto sheet-type magnetic copy media.
2. Description of the Prior Art
Processes for bulk duplication of magnetic records have long been sought in order to reduce the expense of producing copies thereof. Bulk duplication processes are those in which all of the magnetically recorded information is copied essentially simultaneously, as opposed to serial duplication processes, such as the process wherein a master medium having a master magnetic record thereon is moved past a playback head to generate an electrical signal which then drives one, or more recording heads in parallel, to reproduce the magnetic record from the master medium onto a copy medium.
It is known to bulk duplicate magnetic records by contacting a magnetic master medium with a magnetic copy medium, preferably having a coercivity less than that of the master medium, to cause the magnetic fields associated with the master record to alter the magnetization of the copy medium. In such a process, it may be preferable to apply an external magnetic field to bias the magnetic state in the copy medium, thereby enhancing the alteration of magnetization of the copy medium. See U.S. Pat. No. 2,738,383 (Herr & Marchant). To the extent that such a technique is used with a conventional magnetic tape format, it is not truely bulk duplication, since the master tape and copy tape must be run from separate supply reels, momentarily contacted while in a signal transfer stage and then rewound on takeup reels.
U.S. Pat. No. 3,602,649 to Rin describes a device for contact duplication of magnetic records onto sheet-type magnetic copy media wherein a master sheet is contacted with a copy sheet and a magnetic field is applied to the contacted sheets. While such a device enables true bulk duplication of the recorded information, full economies of mass bulk duplication are not afforded inasmuch as no capability of automatically contact duplicating the magnetic record from the master sheet onto a plurality of copy sheets is provided.